The image, catalogued as St. Joseph AVR 62, shows the ghostly outline of what appears to be half of a circular cropmark, measuring somewhere between 25 and 50 metres across. This ancient enclosure wasn't alone; it seems to have been positioned at one end of a larger oval enclosure, though only half of that structure is visible in the photograph as well.

These cropmarks represent the remains of what's likely to be a ringfort, one of thousands that once dotted the Irish landscape during the early medieval period. The site occupies an enviable position on good agricultural land, with sweeping views eastward over Lough Foyle. Despite its promising location and the tantalising glimpses offered by aerial photography, the site hasn't been inspected on the ground, leaving many questions about its original purpose and inhabitants unanswered.

The discovery forms part of the comprehensive Archaeological Survey of County Donegal, compiled by Brian Lacey and his team in 1983. This ambitious project catalogued field antiquities spanning from the Mesolithic period right through to the 17th century, providing an invaluable record of the county's rich archaeological heritage. The aerial photograph technique used to identify this site has proven particularly useful in Ireland, where centuries of farming have levelled many earthworks that remain visible only as variations in crop growth during certain weather conditions.